1. Field of the Invention
This invention relates to an IC card adopting a thermoplastic resin with a short solidification time, a hybrid integrated circuit device, and manufacturing methods therefor.
2. Description of the Related Art
Recently, good use of IC cards has been made in various places. For example, IC cards are in demand for ski lift tickets in a skiing ground, train tickets, a book of swimming pool tickets, etc., including credit cards; it is desired that the IC cards can be used even under hostile conditions.
Generally, two types of sealing methods are adopted from the viewpoint of cost merit. In one sealing method, such means putting a lid on an insulating substrate on which circuit elements of semiconductor elements, etc., are mounted, generally called a case is adopted for sealing. This structure is a hollow structure or a resin is poured into the hollow structure.
The other sealing method is transfer mold, famous as a semiconductor IC mold method. In the transfer mold, generally a thermosetting resin is adopted, a metal mold is raised to about 180 degrees, and the thermosetting resin is hardened (namely, thermally reacts and is polymerized and solidified) with the temperature maintained, then is taken out from the metal mold as a sealing body. To mount an IC chip on a lead frame, soldering is used, but generally is high-temperature soldering and a problem of solder melting does not arise.
However, the sealing structure using a case requires a margin in a substrate so that the case does not come in contact with elements therein, enlarging the outside size.
On the other hand, as seen from the description given above, the transfer mold involves hardening while heating and thus requires a long time for the process; productivity cannot be improved.
Then, the applicant paid attention to a thermoplastic resin not requiring a long time. The thermoplastic resin is heated and melted without hardening reaction and if cooled, it is solidified (namely, becomes solid without reaction). Therefore, after the thermoplastic resin is poured, it is solidified if cooled; sealing can be provided in a short time. However, to seal with a thermoplastic resin, for example, with injection mold, the resin temperature at the pouring time is high (about 300 degrees) and solder is melted, causing a failure in electric connection of circuit elements mounted in an insulating substrate.
Here, high-temperature solder may be used. However, considering degradation of insulating resin under a conductive pattern, low-melting-point solder is preferred. Then, the invention assumes that solder at about 180-250 degrees is adopted in the description to follow.
Generally, the rear face of an insulating substrate is exposed and there is a problem in insulation property between IC card insulating substrate and IC card module attachment chassis. There is a problem in resistance to humidity because of the entry of moisture on the interface between the exposed rear face of IC card insulating substrate and thermoplastic resin sealing the surroundings thereof.
If a substrate inferior in thermal conductivity, such as a printed-circuit board, a flexible sheet, a glass substrate, or a ceramic substrate, is used, solder is melted.
Further, in full mold using transfer mold, a gap is provided between the rear face of a substrate and a metal mold to draw a resin into the rear face of the insulating substrate. Thus, the gap is provided using a pin or by sandwiching the insulating substrate between the upper and lower metal mold parts. However, in injection mold using thermoplastic resin, injection pressure is high (50-200 Kg/cm2), thus the insulating substrate bends, a bonding wire is broken, etc.
A pin trace remains in the pin-supported point and the appearance worsens.